Can Bus; Rfds Frequency Band And Bandwidth - Motorola DIMETRA MTS 2 Installation, Configuration And Basic Service Manual

CAN Bus

MTS 2 and MTS 4, with or without Expansion Cabinet configuration, use different types of
RFDS modules. The following are the distinct differences:
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MTS 2 only has up to two carriers (the frequency that it sends out) and, as a result there are no Post Filters
for a non-duplexed operation. A non-duplexed operation is achieved using a Duplexer as the Post Filter and
not using the receive path of the Duplexer. This configuration does not allow room for a third Preselector
inside the cabinet; however, it is possible to situate one outside the cabinet, for example, on the wall.
CAN Bus
The intercommunication between the RFDS units (the Duplexers, Post Filters, and Cavity Combiners) and the
Site Controller is carried out through the CAN Bus at 125 kB/second. The connectors for the CAN Bus are RJ45
connectors. The CAN Bus is terminated at each end, either by the Site Controller or by an RJ45 terminator.
Each unit is registered at the Site Controller (SC), which specifies the particular channel for each
unit. Every 30 seconds, each unit on the CAN Bus transmits status and alarm information. Alarms are
triggered when any thresholds are exceeded, (failure alarms, software revisions, and so on). The following
common information is available from the CAN Bus: serial number, TrackID, software revisions, and
the Motorola kit number. For each unit, specific information is available, for example, voltage standing
wave ratio (VSWR) for DPMs and tuning information for Cavity Combiners.
The receive path of the Preselector or Duplexer is not connected to the CAN Bus. Because the supply
voltage is supplied from the Base Radio, the Base Radio can withstand a short or 50 ohms connection
to the RX input without the Base Radio or the Power Supply Unit (PSU) being damaged.
For more information on CAN Bus, see

RFDS Frequency Band and Bandwidth

Both MTS 2 and MTS 4 are available in the 350 MHz– 470 MHz range. The bandwidth of
the filters is 5 MHz and the duplex spacing is 10 MHz.
Both MTS 2 and MTS 4 are also available in the 851MHz – 870 MHz range. The bandwidth
of the filters is 19 MHz and the duplex spacing is 45 MHz.
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MTS 2 supports Hybrid Combiners
MTS 4 supports Cavity Combiners or Hybrid Combiners
MTS 2 and MTS 4 do not use the same filters and mechanics for the filter tray
MTS 2 supports up to two RF channels
MTS 4 supports up to four RF channels
Expansion Cabinet supports eight RF channels (four in MTS 4 Prime Cabinet
and four in MTS 4 Expansion Cabinet)
"Site Controller - CAN Bus".
Chapter 7: Radio Frequency Distribution System
6802800U74-N September 2009